[Sarmi]

A wrecking ball of mass 250kg is being used to knock down a brick wall. The ball hits the wall at a velocity of 4m/s. After impact, if three 20kg blocks of wall move at a velocity of 2m/s and two 40kg blocks of wall move at a velocity of 3m/s, using the conservation of momentum, calculate the velocity of the wrecking ball after impact.
Give your answer correct to two decimal places.

Need help please...

[F1Addict]

In simple terms,

Momentum = mass x velocity

The consevation of momentum states that:
Total Momentum Before = Total Momentum After

Does this help?

[oo00oo]

The total momentum before impact must be the same as the total momentum after impact.

Before impact, the only thing moving is the wrecking ball... and it's momentum is .

After impact, the wrecking ball is moving with velocity , and we also have all the bricks with their masses and velocities, so total momentum after is:



Since

We can say:



One equation, one unknown ... solve for .

[Sarmi]

yh...i got the answer as v=2.56ms-1. Is this right?